This description relates to fluid droplet ejection. In some implementations of a fluid droplet ejection device, a substrate, such as a silicon substrate, includes a fluid pumping chamber, a descender, and a nozzle formed therein. Fluid droplets can be ejected from the nozzle and deposited onto a medium, such as in a printing operation. The nozzle is fluidly connected to the descender, which is fluidly connected to the fluid pumping chamber. The fluid pumping chamber can be actuated by a thermal or piezoelectric transducer, and when actuated, the fluid pumping chamber can cause ejection of a fluid droplet through the nozzle. The medium can be moved relative to the fluid droplet ejection device. The ejection of a fluid droplet from a nozzle can be timed with the travel of the medium to place a fluid droplet at a desired location on the medium. These fluid droplet ejection devices typically include multiple nozzles and a high density of nozzles.